Scala Future OnComplete调用 笔记

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在并发Future中建立API调用，和主线程并发地执行任务

  /*调用远程API，获得传入城市的温度*/def cityTemp(name:String):Double = {val url = "http://api.openweathermap.org/data/2.5/weather"val cityUrl = s"$url?q=$name&APPID=981224145dabaaf57b51ff469e7f1acd"val json = io.Source.fromURL(cityUrl).mkStringval pattern = """.*"temp":([\d]+).*""".rval pattern(temp) = jsontemp.toDouble}

import concurrent.Future
import concurrent.ExecutionContext.Implicits.global
import scala.util.Successdef main(args:Array[String]):Unit = {//调用Future.sequence 并发执行Futureval cityTemps:Future[Seq[Double]] = Future sequence Seq(Future(cityTemp("Fresno")),Future(cityTemp("Tempe")))//Future回调函数，当Future执行完成，会自动调用这个函数，输出函数结果cityTemps onComplete {case Success(Seq(x, y)) if x > y => println(s"Fresno is warmer: $x K")case Success(Seq(x, y)) if y > x => println(s"Tempo is warmer: $y K")}//OnComplete调用对变量的影响var temp = 0.0d;cityTemps onComplete {case Success(Seq(x, y)) if x > y => temp = xcase Success(Seq(x, y)) if y > x => temp = y}//主线程继续执行，为了看到OnComplete的执行结果，等待10秒//temp before complete: 0.0println("temp before complete: " + temp)Thread.sleep(10000)//temp after complete: 294.0println("temp after complete: " + temp)println("result complete")}

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